Police are stepping up patrols around Norfolk’s historical sites to combat nighthawking.

Illegal metal detectorists are targeting farmland, heritage sites and other areas of archaeological interest to search for coins and other artefacts to sell on the black market.

Sgt James Butler, who is spearheading the operation for Norfolk police, said: “The east of England is always a target for night hawkers as we have interesting sites, it is something that has been under reported or reported too late.

“Nighthawking is stealing. The landowner owns the land so owns what’s under it, if anything is taken without permission it is theft. Also if there is damage to crops on the land it’s an offence of criminal damage.

“Whether you have permission or not from the landowner, you will be committing an offence if you find something deemed to be treasure, and don’t report it.”

The 1996 Treasure Act makes it the finder’s legal duty to declare any coins, gold or silver over 300 years old to their local coroner within 14 days of finding it.

The coroner will then hold an inquest to determine whether the find constitutes treasure or not, if it is then the finder must offer the item for sale to a museum.

Only if a museum expresses no interest in the item, or is unable to purchase it, can the finder keep it.

If finds are not reported, treasure hunters can face an unlimited fine or up to three months in prison.

Intelligence-led policing and targeted sites are being looked into under Operation Chronos in partnership with Historic England.

Landowners, the general public and people who live near the sites can help safeguard them by reporting any suspicious activity.

Sgt Butler said: “Look for people there who shouldn’t be. Holes in the ground, turf, soil. Nighthawkers work quickly so they don’t always put grass back. Also look out for tyre marks in the grass and general rubbish left behind.”

If you have any questions, queries or information contact heritagecrime@norfolk.pnn.police.uk